1. Field of the Invention
The present invention relates in general to medical instrumentation, and more particularly to intraluminal devices, and still more particularly to guide wires for intraluminal catheters.
2. Description of the Prior Art
The use of intraluminal catheters for treatment of various medical problems within the body is well known. It is also well known that a variety of problems are encountered as the catheter is steered through the selected lumen to a desired point in the body. The path may be tortuous and the point of interest may be difficult to locate precisely. A continuing series of technical improvements and additions have been made in the catheter field to provide devices and methods which can overcome certain of the difficulties. One such series of improvements has resulted in the now well known use of a thin flexible guide wire which can be more easily steered through the lumen to the desired site. A selected catheter, such as a balloon catheter, can then be slid over the guide wire to reach the desired situs in the body.
It is now well known that providing a bend or "J-tip" to the distal end of the guide wire increases maneuverability of the guide wire through the lumen. Such J-tips are often set by the manufacturer of the guide wire, but it is also sometimes advantageous to have the physician or other operator create or modify the bend during an angioplasty procedure.
Certain disadvantages exist in this known prior art. For example, the material most commonly used for guide wires is stainless steel, for example, 304V stainless steel. The formation of a bend or J-tip at the distal end of such a metal wire requires a force which may be inconsistent or irregular thus significantly effecting the strength of the guide wire tip. One way to attempt to increase formability of the guide wire distal end may be to heat the tip. In the present art, the tip is often heated prior to cold working, in the case of stainless steel 304V to a temperature within the range of 700.degree. to 1000.degree. F. This procedure of increasing temperature followed by cold working of the stainless steel results in a less than optimum performance. It is also likely that heating the entire distal portion of the guide wire to the annealing temperature, approximately 1400.degree. F. in the case of stainless steel 304V, may add too much formability to the wire tip, thus negatively effecting its tip strength and steering properties as it is guided through a body lumen.
As a general example of formable tip references in the prior art, see by way of example, U.S. Pat. No. 4,846,186, issued Jul. 11, 1989 to Box, et al; and U.S. Pat. No. 4,838,879, issued Jun. 13, 1989 to Tanabe, et al.